Generating foldout menus in php

This may not be directly php related but I'm hoping that generating the code with PHP will keep it on topic. I'm looking for a way to generate dropdown/foldout menus (horizontal and vertical) on the fly, but all the javascript solutions I've seen use absolute or relative pixel positioning, which means I can't use them because I don't know at the time of generating a specific menu item how many pixels across or down the preceding items have already used. I'm currently using a javascript menu that works really well, but all the top-level menu items have to be preset with specific x-y pixel coordinates, and all the subsequent items are then relative to the top-level items. So I can generate the second-level and subsequent items on the fly but not the top-level items. Is there a way to use css or dhtml or something else (maybe something in javascript that I missed) to do this? Thanks Arno